Telephone system



Aug. 14, 1928.

M. B. STAZAK TELEPHONE SYSTEM Filed Jan. 11, 1926 2 Sheets-Sheet 2 TZzchaelfi E; 7 9 a.

Patented Aug. l4,

rarest" MICEAEL B. STAZAK, OF CHICAGO, ILLINOI$, ASSIGNGR TO KELLOGG SWITCE-IBOABD AND SUPPLY CGIv'IPANY, OF CHICAGO, ELLINOIS, A CQRPOBATI ON OF ILLINOIS.

TELEPHONE SYSTEM.

Application filed. January 11,1926. Serial No. 86,438.

My invention relates to a telephone system to connect subscribers lines by means of a manual or semi-automatically operated eonneeting circuit and is adapted to be used in exchanges which interconnect both magneto and common battery subscribers lines. A large number of exchanges are located. in towns or cities having common battery local lines. These exchanges often have country subscribers who have magneto telephone lines, and as the toll or country subscribers often wish to converse with. local or town subscribers, it is necessary to have a cord circuit which may be used to interconnect the two kinds of lines. The present inven-' tion provides a high impedance, tull universal cord circuit arranged for flashing recall automatic ringing, lreyless listening on common battery connections, and means to cut out the repeating coils on a through magneto line connection. V

lhe ob'ect of the present invention is to provide a system of the above character which is devised to complete connections from a subscriber having a magneto type substation to another magneto type substation, or to a common battery type substation or from a subscriber having a common battery type substationto another common battery type substation or a magneto type substation.

One of the features of my invention is keyless listening on common battery conneetions, means being provided whereby the operators circuit: is automatically connected to the calling subscribers line to permit the operator to converse with the subscriber. But when a subscriber having a magneto type substation initiates a call'the above noted listening means are not actuated and it is necessary for the operator to. threw her listen- Ming ltey beiore a conversational circuit is completed :trom the subscriber to the operntor.

Another feature is the provision oi a circuit having both automatically and manually operated means for calling the subscriber wanted. It the called subscriber is provided with a common battery substation the auto matic harmonic ringing means may be employed and the ringer at the substation will be actuated intermittently until the sub seriber answers or the calling subscriber abandons the call and replaces his receiver upon its switchhook. .It the called sulr scriber has a magneto type substation, it is necessary for the operator to actuate her ringing key every time she wishes to actuate the ringer of the substation wanted. Means are also provided whereby the automatic ringing apparatus is returned to normal when the called subscriber removes his re.- ceiver from its switchhool: to answer a call.

Still another feature is the provision of means whereby the calling subscriber may abandon a call and stop the automatic ringing means from functioning by replacing liis receiver upon its switchhook.

Another feature is the provision of means whereby when a call is extended from a lung neto type substation to another magneto type substation the repeating coils, which are used in making the connection between common battery type substations, are removed trom the circuit.

The above features as well as others, will be more clearly pointed out in the ensuing specification and appended claims. For a better understanding of the same reference may )9 had to the accon'upan ing drawings which, when placed together with part 2 to the right of part 1, and with the lines of part- 1 continued in the corresponding lines of part 2, illustrate one complete circuit.

At the extreme left of part 1 two subscribers substations A and M are shown, A being of the common battery type and M of the magneto type. The substation A is connected to a line circuit LC at; the central ofiice by a pair oi lines 1 and 2 connccted in multiple to a number of jacks J which appear at a number of operators positions. A line relay LR is adapted to close a circuit for a number of lamps L which are associated with the jacks J. This is the usual system employed to enable a plurality of operators to be notified of an incoming call. A cut oil relay CO is also provided which when actuated will deenergize the line relay LR.

The magneto type substation- M is connected by a pair of lines 3 and a to the mainexchange where it terminates in a line circuit LC which has multiple jacks J and lan'ips L similar to the jacks J and lamps L of the line circuit LC. A line relay LR and a cut oti relay C0 are also provided.

The cord circuit C is provided to extend a connection from the substations A and M to the substations A. and M, part 2, which llll and a calling plug back on a calling subscribers line. The ringing key RK 1S adaptedto connect gcncrator G to the line to actuate the call bell when a connection is extended to a magneto type substation. The four party key PK is associated with four ringing generators G, G, G and G which provide harn'ionic An interrupter I intcr inittently connects the ringing current to the called subscribefs line by alternately closing and opening a circuit for a ringing relay RR over a circuit maintained by a ring ing control relay RC. A repeating coil is composed of four windings B, B, B and B and has two condensers D and D interringing current.

I posed between the coils.

,t 'acts its armature 11. V for thcluie lamps I A detailed description of the completion of a call from a common battery type substationto another common battery substation will now be given: 7

Vl hen the subscriber at the substation A removes his receiver 5 from the switchhook '6 a circuit is completed for the line relay LR traced from.battery. through relay LR, closed contact 7 of relay CO, line 1, inductance 8, closed switchhook contacts, transmitter 9, line 2, closed contact 10 of relay CO to ground. Relay LR, upon energization, at-

to complete a circuit L traced from battery through the lamps L, and closed contact 11 to ground. The lamps L which are located at diiicrent operators positions are lighted to indicate that a subscriber is calling. One of the answeringoperators will now insert into one of the jacks J an answering plug, such as the plug AP of the cord C illustrated. lVhen the plug AP is inserted into the Jack J, a circuit is completed for the cut oft relay'CO and the relays 12 and 13 traced from battery, through relays 12 and 13, con.- ductors 14 and 15, sleeve contacts ot'the plug AP and jack J. to ground through the cut off relay CO. Relay CO thereupon attracts its armatures 7 and 10 which break the energizing circuit for relay LR whcreuponits armature 11 is IGJUIDQCl to normal; thusinterrupting the circuit for the lamps L. The relays 12 and 13 their armatures thus completing a circuit traced from battery, through closed contact 16 of relay 13, conductor 17, alternate contact 18 of relay 12, conductor '19 to point 20 where the current divides part of it flowing through conductor '21 and switching reto' ground; the other part flowing through conductor 19 to make before break Contact 23, conductor 24- and repeating coil conductor 59, ed plug and ]ack are energized and attract' relay to ground. Relayssvf and RPR induction coilOI, conductor 40, normal contact 4:1, conductors 42, 18, and 44, closed contact of relay SlV, conductor -16, normal contact 47, conductor 48, heavy conductor S, normal contact 49 of ringback key RB, ring contacts of the connected plug and jack, line 1, induction coil Sand back to trans? mitter 9. The battery current for this talking circuit is supplied by a' circuit traced from battery, relay ASR, conductor 50, al tcrnate contact '51 of relay 'SVUcondu'ctor 52, winding 1B of the resistance coil associated with the repeating coil,jrepeating coil winding B, then over the above described circuit through the subscribers loop, repeat.- ing coil B resistance coil 1B conductor 53, to ground through alternate contact 54: of relay SW The relayiASR is energized over this circuit and attracts itsarniature 55 which closes a circuit for relay E, traced from battery, through the relay E, conductor-56, to ground at alternate contact 55 of relay ASH. Therelay E thereupon attracts its armatures 57 and 58, but noaction is causedat this time bythe energization of relay-E.

The operator having ascertainedthe number of the subscriber wanted takes the calling plug GP associated with the plug AP and makes the busy test in the usualmanner. Assume that the wanted subscriber is the one marked A on the drawing and that the line is idle. The operator will inscrt the plug GP into a 'jack substation A completing a-circuit traced from battery,

to ground through relay C0 The relays CO and H and IR are all energized. 'Relay CO attracts its armatures to prevent the line relay LE traced from operating when the subscriber at A answers the call; battery, through relay T, conductor 71 to ground at closed contact 72 of relay 1R; thus energizing relay T. Relay H attracts its armature 60; which completes a circuit for the calling supervisory relay GER-traced from battery, through relay CSR and conductor 51 to ground'throughclosed contact 60 of relay H. .RelayCSR energizesand interrupter relay IR, relay H, sleeve cont-actsiot' the connect J associated with the Relay IR} closes a circuit from insane attracts its armatures thus disconnecting the operators set from the calling line by opening contacts 28 and 47 The closing of contact 62 completes a circuit for the calling supervisory lamp CSL traced from battery,

polarized relay, PR.

The operator next presses the proper plunger of the party ringing key PK to transmit ringing current to the call bell at the substation A. Assuming that generator G is of the proper frequency to actuate the call bell, the operator will actuate plunger 73 which will remain actuated after the pressure is released from it. The'end springs ES are momentarily actuated when the plunger 78 is depressed and complete the following circuit for the ringing control relay RC. Battery, relay RC, conductor 77, actuated end spring 8, conductor 69, to ground at normal contact of relay RDR. The ringing relay-RR- is momentarily energized to give an instantaneous or preliminary ring to the wanted subscriber. Relay RE is momentarily operated by current flowing from battery, relay RR, conductor 79, end spring 80 which is closed, conductor 81 to ground at closed contact 82 of relay RC which is locked up by current flowing from battery, through the winding of relay RC, conductor 83, normal contact 84 of the flashing recall relay FEB, conductor 85, alternate contact 05 of relay RC, conductor 66', alternate contact 67, conductors 68 and 69, to. ground at normal contact 70.

The attraction of contact 65 by relay RC interrupts the circuit forthe calling supervisory lamp CSL which-is thereupon etiaced. hen the relay T was energized a new holding circuit was completed for the repeating coil relay RPR which is maintained by current flowing "from battery, through the closed contact 23, conductor 24 and relay BPR to ground. Upon the energization of relay RC. a circuit is completed for the ringing relay RR traced from battery, through thelower winding of relay BR, conductor 86, closed contact 87 of relay RC, conductor 88, closed contact 89, of relay IR to ground through the constantly rotating interrupter I. This circuit is alternately completedand interrupted by the interrupter I as long as relay RC remains energized and consequently the ringing relay RE is intermittently energized and attracts its armatures to connect ringingcurrent to the called sub ,scribers line over the following circuit.

From, ground, through the ringing generator G plunger 73, conductor 90, alternate contact 91, over the heavy conductor S through the closed contact of the ringing key BK, conductor S ring contacts of the connected plug and jack, out over the line 2 through the call bell 25 at the subscribers substation, back over the line 1' through the tip contacts of the connected plug and jack, alternate contact 92, normal contact 129 of the key BK, alternate contact 98 of relay RR, conductor 94, and plungers and 96 to ground. The ringing current is intermittently connected to the subscribers line until the called subscriber answers the call, or the calling subscriber abandons the call. lVhen the called subscriber removes the receiver 5 from the switchhook 6 a circuit is estab lished for the ringing disconnect relay BDR traced from battery, relay RDB, conductor 97, alternate contact 98, conductor 99, Windings IB and B, conductor S, alternate contact 100, normal contact 91 of relay RR, which is alternately energized or deenergized, closed ringing key contacts BK, ring contacts of the connected plug and jack, out over line conductor 1 through the closed iigwitchhook contacts at the substation, back over line conductor 2, through the tip contacts of the connected plug and jack, alternate contact 92, normal ringing key con tacts. normal contact 93, alternate contact 101, through winding B of the repeating coil, resistance coil winding 1B conductor 102, to ground at alternate contact 103 of relay IR. The relay RDB remains energized as long as the called subscribers receiver is oflt its switchhook. Upon the energization of relay RDR the relay BC has its locking circuit broken at contact 70 and returns to normal. This breaks the circuit for the ringing relay RR which returns to normal.

Each time the rin ing relay HR is ener gized, to transmit ringing current to the called line, the calling subscriber receives an audible ringing signal over a circuit traced from ground, through generator G, coil 104, condenser 105, conductor 10G, alternate contact 107, conductor 108, alternate contact 101, coil B winding 1B conductor 102 to ground'at contact 103 of relay IR. This current in coil B sets up a current in coil B which passes over the heavy conductors to the subscribers station A where the induced current causes a vibratory action in the receiver 5 and thus notifies the calling subscriber that the called subscriber is being signaled. A talking circuit now exists be tween the calling and called substations over circuit formed by the heavy conductors, the repeating coils, B, B, B and B and the condensers D and D This circuit is closed at alternate contacts 109 and 110 of the repeating coil relay RPR which is main-.

remains energized as long as the plug OP .is in the jack J Assuming now that the called line was busy, when the operator tested the line by touching the tip contact of the plug GP to the sleeve contact of the jack J battery potential will be on the sleeve contact of the jack- This'battery potential will be caused by current flowing through relays IR andl-I of another cord circuit C connected to a multiple jack of the called line. A circuit for the'busy test relay BTR will be completed traced from battery on sleevecontact of the jack, tip contact of: plug CP,-normal contact 92, conductor 11]. to ground through relay BT11. Relay BTR attracts its armature 112 to complete a circuit traced from battery through inductance 113, armature 112'and through the'winding y of the operators induction coil OI to ground. The current passing through the winding Y induces current in the winding X of the coil OI which flows through normal contact 37, conductor 36,head set HS,'conductor 35, normal contacts 34 and 114 back to the other side of the winding X. This produces a characteristic click in the head set HS'Which is the recognized busy-signal.

' its armature 118 it establishes a locking cir cult for itself traced troi Upon receivin this bus si nal the o ierator the will inform thecalling subscriber that wanted line is busy and he will replace his receiver upon its switchhook to return the apparatus in the cord circuit to normal in a manner hereinafter described.

It the called subscriber does not respond when the call bell is actuated, the calling subscriber may at anytime abandon the call by replacing his receiver upon its switchhook. lVhen the receiver is replaced the circuit "for relay ASH is interrupted at the swil'chhool; contacts and contact returns to, normal interrupting thecholding circuit for relay E.. The return of contact 57 of relay E to normal completes an energizing circuit for flashing recall relay FRR traced from battery through relay FRR, normal contact 57 conductor 115, alternate contact 116, conductor 117-and contact 72 of relay IE to ground. \Vhenrelay FRR attracts n battery, through conductor 115 and as previously. deof armature: 84;

the relay, its contact 118, contact 721 to ground, scribed. The attraction opens the locking circuit for the ringing 1 control relay RC which returns to normal and disconnects the ringing current from the called line. lVhen the contact 55 of relay ASE returned to normal it closed a circuit torjthe answering'supervisory lamp ASL which was illuminated bycurrent flow I ing from-battery through closed contact 16,

lainpASL, alternate contact 119 of relay 12,

'VVhcn' the conversation has been finished the subscribers replace their receivers and disconnection takes place'in the following manner: \Vhen the calling subscriber replaces his receiver the circuit for relay ASE is interruptedand the said relay returns to normal and causes the following action: The relay 1*] deenergizes, the relay F ER is energized andthe lampASL is lighted to inform the operator of thedisconnectionot the calling subscriber, all as previously described. r I

' hen the called 'subscriberre'places his receiver the circuitfor relay RDR is broken at the switchhook contacts and it returns to normal. I-ts contact completes acirc'uit for the calling supervisory lamp CSL which is thereupon "i'llumin'ated by current flowing from battery, closed'contact 62, conductor 63, lamp CSL, conductor 64, normal contact 65, conductor 66, alternate contact 6?, con ductors menace to ground at normal contact 70. Both the lamps ASL 'and'CSL being now lit, the operator will know the conversation has been completed and will withdraw the plugs AP and GP "from the jacks J and J *Wheri AP-is withdrawn the circuits otrelays CO, 12 and 13 are broken and they return to normal, causing the deenergization of relays FER and SW. When the plug CP is withdrawn the circuit for relays CO H and IR is broken. Relay IR returns to normal and at its contact 72 interrupts the circuit for relayT which returns to normal and opens the circuit of relay RPR at contact 28; Relay H- re.- turning to normal opens the circuit for re: lay CSR which breaks the circuit for relay D at contact-62. The 'apparatus'used to complete the call is now all at normal and ready for another call. The lower windings of the relay E and CSR are, non-inductively wound so as to drain the relays 12 and 13 and IR- and H when the plugs AP and'CP are removed from the respective jacks 'to prevent the; operator from receiving a disagreeable shock 7 should she accidentally grasp the sleeve ofeith'er plug when removing them from their'respective jacks. V If, after the completion of a call and be fore the plugs'have been withdrawn from theirrespective jacks, the calling subscriber desires to make'a recall he willagain remove his receiver from its switchhook which will cause the answering supervisorylamp"ASL to flash which will'inform the operator thirt the subscriber desires to make another call. This is accomplished in the iollowing manner: When the upper contacts of switchhook 6 are closed a circuit for the relay ASB- 1s again completed through the subscribers loop as before described. 7 Relay ASH is energized and attracts its armature which closes an energizing circuit for the relay E Which closes its contact 58 to establish a circuit for the lamp ASL over a circuit traced from battery, lamp ASL, alternate contact 119, conductors 120 and 121, alternate contact 122 of relay FER, alternate contact 58 and through the constantly rotating interrupter l to ground. The circuit for the lamp ASL is intermittently interrupted by the interrupter I which causes the lamp ASLt-o flash. The operator recognizes this as a recall signal whereupon she will Withdrawithe calling plug GP to deenergize relays lR-and H which in turn deenergize relay CSR. lVhen the contacts 28 and 47 return to normal, the operator will again be connected in a conversational circuit with the calling subscriber-and can inquire as to his Wants. It Willbe remembered that the relays 12, 13 and FER were energized during the preceding call and have not been returned tonormal because the operator had 7 not Withdrawn the answering plug.

The cord circuit C may also be used to complete calls between subscribers lines having magneto type substations. Assume that the subscriber at M desires to converse with the subscriber at M. The subscriber at M Willoperate his hand generator HM Whi h will cause the energization of line relay Ll in the usual manner. Relay LR attracts its armatures 128 and 125.. The attraction of armature 123 allows the spring .12 1 to drop down and as the relay LR is deenergized when the hand generator HM is no longer actuated the contact 125 returns to nornnil. Contact 123 is prevented from returning to normal by the construction of the spring 12 1. A circuit for the lamp L is now completed and the same is actuated by current flowing from battery, lamp L, normal contact 125 to ground at spring 124; 7 Upon noticing the glowing lamp L an operatorwill inserta plug AP into one of the multiple acks J associated with the lamp L. A circuit is now completed for current flowing from battery through relays 12 and 13, conductors 141 and 15, tip contacts of AP and J to ground at relay CO. The relay 12 is not energized at this time because of the'high resistance of the-cut-oit relay CO. \Vhen CO is energized it attracts its armatrue 126 which is connected to spring 124: by a shaft 127. The spring 124: is raised and the contact 128 returns to normal. The lamp L is eii'aced due to the interruption of its energizing circuit at spring 124:. The operator then actuates her talking key TK and listening key LK to learn the Wants of the calling subscriber.

Upon obtaining the information that the Wanted subscriber is the one at substation M, she will make the busy test and ii the line is idle, insert the calling plug (JP lnto the proper jack J whereupon a circuit is completed for current flowing from battery, through relays IR and H, conductor 59, sleeeve contacts of Cl and J and through relay CO to ground. clay IR is not energized because Oil the high resistance of relay CO Relay H attracts its armature and closes an energizing circuit for relay CSR traced from battery through relay CS1, conductor 61 to ground at alternate contact 60. Relay CSR completes a circuit for relay D traced from battery through.

closed contact 62, conductor '74, relay 1), conductor 75, to ground at normal contact 16. The attraction of armature 128 01": re-

lay D opens the energizing circuit for the lamp ASL which was lighted When relay 13 was energizer. The said lamp ASL was illuminated by current flowing from battery th rough contact 16, lamp ASL, normal contact 119 and normal contact 128 to ground.

The operator Will next actuate her ringing key RK to connect ringing current to the calledline to actuate the call bell at substation M. The substation called may be equipped for harmonic ringing and it such is the case the operator Will actuate the pro-per plunger of the ringing key PK and ringing current will betransmitted to the called line over a path previously described. However, it will be necessary for the opera tor to actuate theplunger for every impulse of current transmitted, as in such a connection the automatic ringing means are not used. The circuit Within the cord over which this ringing current is supplied is the same as that previously described. Assuming that the called substation M is equipped with straight line ringing, the actuation oi the ringing key BK will transmit ringing current over a circuit traced from ground through the ringing generator G", actuated Contact 129 of key RK, alternate contact 92, tip contacts of Cl and J line 3, through the hand generator contacts, call bell CB, line 1, ring contacts of J and GP, to ground at alternate contact 130 of key BK. As soon as the called subscriber removes his receiver from its switchhookand the operator releases her ringing key BK the subscribers at M and M are in a conversational circuit traced from M, line 1, tip contacts oi? J and AP, conductors N and N, normal contact 101, conductor N normal contact 93 conductor N normal contact 129, conductor N", alternate contact 92, conductor N tip contacts of GP and J out over the line 3, through the substation M, and back over line 4, ring contacts of J 3 and GP, conduc lit) cuit is completed for the relay PR whichis tor S, normal contact 130, conductor S normal contact 91, conductor 8?, normal contact 100, conductors SJand S, ring contacts of AP and J, line 3 and'substantion M. It

will be seen that in this connection the repeating COllS are not used but are cut out of the circuit. In a connection between a pair- .Upon the disconnection of a connection between two magneto lines only one lamp, the answering supervisory lamp ASL, is actuated and when the operator notices that the lamp ASL is glowing she will withdraw the connecting plugs and the apparatus will return to normal. .lVhen the subscribers at M and M finish their conversation, they will replace their receivers and actuate their hand generators HM and HM to ring oft. An energizing circuit for the polarized relay PR is completed and it is actuated by current flowing from one contact of hand generator HM, line 3, tip contacts of J and GP, conductor N alternate contact 92, conductors N, N 1* and N, windings B and IE conductor 53, normal contact 54, conductors 130 and 131, winding 13 1, condenser 132, winding 135, conductor 133, normal contact 51, conductor 52, windings 1B and B, conductors S, S S and S, ring contacts of CP and J line 4 and to theother contact of the generator HM. When the hand generator HM is operated an energizing ciractuated by current flowing from one con tact of HM, line -l, tip contacts of J and AP, conductor N 'to winding B and then over the previously described path to winding 13 then back over conductor S, ring con tacts of AP and J, line 3 to the other contact HM. It will beseen from this that the actuation of either hand generator HM or HM will start the operation of the disconnecting means. Relay PR is energized and attracts its armature 76 which interrupts the circuit for relay D which thereupon returns to normal and closes its contact 128 which completes an energizing circuit for relay V traced from battery, closed contact62, conductor 74, relay V and normal contact 128 to ground. The relay V'energizes and closes a locking circuit for itself traced from bat.

tery over the above mentioned path through relay V, its own contact 136, conductor 13?,

' to ground at normal contact 138 of the listening key LK. The relay V remains on erglzed, under the control of-the listening 'lrey LK to complete an energizing circuitfor the lamp ASL to inform the operator that the subscribers have finished their con'versa-r tion. The lamp ASL is lighted bycu'rrent and CP. The withdrawal of opens the circuit for the lamp ASL. The V withdrawal of GP causes'the deenergization of relays CO and H. Relay'H opens the energizing circuit for, relay CSR which opens its contact 62 and thus breaks the energizing circuit for relays Vand D which return to normah Relay 7V opens another point in the circuit of'lamp ASL at contact 136. All the apparatus is now at normal and ready to complete another call.

The cord circuit of my invention may also be used to complete calls from a subscriber having having a common battery type substation. In the completion of such a call the operation is as ates his hand generator and the action is similar to that described in a magneto to magneto connection. Assuming the calling subscriber wishes to talk to the subscriber at A, the operator inserts the callingplug GP into the jack J associated with the substation A. The relays CO H and IR are energized as before described. Upon the energization of these relays, energizing circuits for the relays CSR and T are completed. RelayT operates to close an original energizing circuit for the relay RPR through its contact 23. Therelay R-PR attracts its armatures 109'and 110 to connect the repeating coils into the circuit. The ringing mechanism is actuated and the operation is similar to that described for a common battery to common battery substation connection. Battery current for talking is supplied to the called line from battery through relay RDR out over the line and back to ground at alternate contact 103 of relay IR. A'resistance 140'tends to offer a free path for the current and thus eliminates any muttling ofthe voice currents. This action takes place in all connections in which the called substation is of the common batterytype.v

Upon the disconnection ofsuch a connectionboth the lamps ASL and. CSL glow to inform the operator that the conversation has been completed.

a magneto type substation to onefollows: The subscriber at M actupurposes When the called sub-'1 scriber replaces his receiver'the' relay RDR is deenergized and its contact TO'completes a circuit for the lamp CSL traced from battcry, contact 62, lamp CSL, normal contact 65, alternate contact 67, to ground at normal contact 70. When the calling subscriber replaces his receiver he actuates his hand generator or magneto HM. This energizes the relay PR which, at its armature 76, breaks the energizing circuit for relay D which returns to normal and at its contact 128 completes an energizing circuit for the relay V. The relay V locks itself up and establishes a circuit for the lamp ASL which is caused to glow by current flowing, from battery, through lamp ASL, normal contact 119, alternate contact136, to ground at normal contact 138 of LK. Upon noticing that both lamps are glowing theoperator will withdraw the connecting plugs and the apparatus will return to normal, all as before described. The present cord circuit is also adapted to complete a call from a common battery substation to a magneto substation. In such a case the action following the insertion of the plug AP in the jack ofthe calling subscribers line up to the time when the operator inserts her calling plug OP into a jack J associated with a magneto type substation such as M, is similar to that taking place when a connection is established from one common battery *line to another. Upon the insertion of the answering plug AP, the relays CO, 12, 13, SW, ASR and E are operated. When the calling plug CP is inserted into the jack J the relays CO and H are operated and cause the energiz'at-ion of relays CSR and D. The operator next presses the manual ringing key RK and transmits ringing currentto the called subscriber as previously described,

Upon completion of the conversation the subscribers replace their. receivers and the called subscriber operates his hand generator HM to actuate the relay PR over a circuit traced from magneto, line 3, tip contact of jack and plug, conductors N N N and N alternate contact 101, windings- 13 and IE conductor 102, contact: 103, conductor 131, relay PR, conductors 133 and 150, normal contact 98, conductor 99, Windings IB' and B conductors S, S S and S ring contacts of plug and jack, andline 4" back to the magneto. The energization of relay 'PR' deenergizes relay D which causes the relay V to operate to light thelamp- CSL by current flowingfrom battery, contact 62,

lamp 'CSL, contacts 65,: 67,. 151' and 136 to ground at contact 138 of key LK'. When the calling subscriber replaced his-receiver the relay ASE was decnergized and opened the circuit of. relay E. Relay ASE returning its cont-act 55 to normal establisheda circuit which caused lamp ASL to glow by current flowing from, battery, closed contact 16, lamp ASL, alternate Contact 119, to ground at normal contact'55. The operator will thenrestore all the apparatus used by withdrawing the plugs AP and CP.

From the foregoing description it will be seen that the same cord circuit can be used to extend a call from a common battery substation to another common battery substation; from a common battery substation to a magneto type substation; from a magneto type substation to another magneto type substation; or from a magneto type substation to a common battery type substation.

While I have described a preferred embodiment of my invention, it is to be understood thatI do not desire to be limited to the exact application as illustrated and described, but intend to cover'all such changes and modificationsas come within the spirit and scope of the appended claims.

Having described my invention what I desire to claim as new and secure by United States Letters Patent is:

1. A telephone system of the character described including a plurality of subscribers lines, some of said lines ha -ing common battery substations and the remainder having magneto type substations, a cord circuit provided with answeril'ig and calling terminals for connecting any two of said lines, a set of repeating coils for said cord circuit, means associated with said answering and calling terminals eifective to include said coils in or exclude them from said circuit, and a relay associated with said means being arranged to include said coils in said circuit whenever one of the connected lines is of associated with said answering and calling terminals and a relay controlled by said means for connecting the sald coils into the conversational circuit when one of the lines is of the common battery type, but excluding said coils when both connected lines are of the magneto type. r

3. A telephone system of the character described including a plurality of subscribers lines: some of which are equipped with common battery and the others with magneto type substations, a cord circuit provided with answering and calling terminals for connecting any twoof said lines into a convesational circuit, a set of repeating coils and means associated with said answering and calling terminals and a relay controlled by. said meansioperative whenever one of the connected substations is of the common hatoperating the signal of the called subscriber,

a set of repeatingcoils, and means associated with said answering and calling terminals and a relay controlled thereby for connecting said repeating coils into the conversational circuit between the said substations.

5., A telephone system of the character described including a cord circuit, a plurality of subscribers lines, a set of repeating coils for said cord circuit andmeans anda relay controlled. by said means arranged to include said repeating coils in the conversational circuit when one of the connected lines is of the common battery type and to exclude said repeating coils from the conversational circuit when both the connected lines have magneto type substations. r 6., Atelephone system of the character described including a cord circuit provided with answering and calling terminals arranged to connect a common battery'type line to another common battery type line'or 1 coils from the conversations.

both the connected lines have magneto type,

to a magneto type line, a set of repeating coils, means associated with said answering and calling terminals and a relay controlled by said means for including said coils in-the conversational circuit between said lines, a recall lamp, and means in said cord circuit whereby the calling subscriber may upon" the completionof one call institute a recall by again removing his receiver from its switchhook to cause said lamp to flash.

A telephonesystem of the character described including'a plurality of subscribers liLfS part having common battery and part magneto type substations, a cord circuit for connecting any of said lines into a conversational circuit, a set of repeating coils, means in said cord circuit and a relay controlled by said means arranged to include said repeating coilsin the conversational circuit when one ot the connected lines is of the common battery type and to exclude said repeating substations, a pair of: ringing current supply sources, one of said sources consisting of a plurality oi ringing generators comprising a set adapted to supply ringing current to common battery lines exclusively, said other source comprising a single ringing generator adapted to supply ringing current to 1nag--:

neto type substations, means in said cord circuit operative upon the connection of said L circuit when cord circuit witha common battery substation for automatically supplying ringing current to subscribers lines from said first ringing current supply source, and manualringing means for supplying r ngin current jlrom the other or said pair orringing current supply sources to subscrlbers lines having magneto type substations.-

8. n telephone system of the-character descr bed including a cord c rcuit adapted to connect subscribers lines havlng either common battery or magneto type; substations into a-conversationalcircuit, a plurality of substations of'each type, a set of repeating coils, means in said cord circuit and a relay controlled by saiclineans adapted to include said coils insaid conversational connection when one of the connecting lineshas a common battery substation-and to exclude said coils from ya connection between two magneto type lines, means for automatically applying ringing current to, acommon battery line andmanual means for connecting ringing current to ,a magneto type line; V

9. A telephone system of the character detill scribed including a core circuit, a calling plug" and an answering plug for said cordcircuit, a plurality of subscribers lines havingcommon battery and magneto type substations, a line jack for, each of-said lines, an operators set, automatic means for connecting said operators set to said cord'circuit, said answering plug adapted to be connected to a line jack associated with aconnnonbattery line to cause said automatic means tooperate 'to connect said operators set to said cord circuit,and manual means'adapted to connect the operators set to the cord circuit when the'answering plug isinserted into a jack associated with a magneto type line.

10. A telephone system of the character described including a cord circuit, a-calling plug and an'answering plug for said cord circuit,afplurality of lines some having com" mon battery and others magneto type substa tions, said cord circuit being arranged to conne'ctany two'ot' said lines into a conversational circuit, a line jack for each of said lines, an operators set, automatic means for connecting said operators set to said cord circuit,said answering plug adaptedito be inserted into a line jack associated with one of said" common battery lines to operate said automatic means, and automatic means includinga relay fordisconnecting the said operator.s set fromrhe said-cord circuit,

said calling plug adaptedito'beinserted into a line jack associatedwith any-one of the plurality lines to complete an energizing cir-Q cuit itor the said relay to disconnect the 'said operators set from the sald cord circuit.

In testimony whereof I have; signed this specification;

' MIGianni-1 B;"srA'zAK. 

